Intrauterine devices known to the prior art are typically secured within the uterine cavity by conforming the device to the contours of the cavity. Since the uterine cavity increases in cross-section in the direction of the fundus, conventional means for retaining the device within the cavity are adapted to this conformation. For example, devices in common use include T-shaped devices, wherein the sidearms of the "T" extend into the wider section of the cavity, thereby retaining the device within the uterus. Notwithstanding the shape-adapting conformation of such devices, they are frequently involuntarily expelled, owing to especially strong contractions of the musculature of the uterus, failure of the device to conform adequately to the conformations of individual uterine cavities, or for other reasons.
It is accordingly an object of the invention to provide a method of contraception comprising employing an intrauterine device (IUD) which is reliably retained within the uterine cavity, and which is not dependent for retention upon a precise conformation.